Bio 220 - Chapter 6 - Communication, Integration, and Homeostasis

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The most rapid intracellular responses to signals result from activation of receptors that are also...

ion channels
The ion that controls the widest variet of intracellular activities is

calcium
Signal molecules that degrade most rapidly, resulting in very brief effects, are

gases such as nitric oxide
The neurotransmitter norepinephrine ____

causes some blood vessels to dilate and others to constrict, because different vessels have different receptors for norepinephrine.
Compared to endocrine reflexes, neural reflexes ______

respond rapidly but are very brief
Cells that respond to signals are usually called

targets
Why do some normal cells fail to respond to a chemical signal?

some cells lack the necessary receptors.
Receptor molecules are located in the:
- cytosol
- nucleus
- outer cell membrane
Lipophilic hormones bind to receptors

inside the cytoplasm or nucleus
This messenger:
changes the regulation of ion channels
increases intracellular Ca+ concentration
changes enzyme activity

Second messenger
Evaluates incoming signals and compares it with the setpoint

Integrating center
Stabilizes the variable being regulated

negative feedback
membrane-spanning proteins that communicate in gap junctions

connexins
A chemical that is secreted by a cell to act on cells in its immediate vicinity is called a

paracrine
If the signal molecule acts on the cell that secreted it, the chemical is called an

autocrine
target cell inserts more receptors into its membrane

up-regulation
Signal molecule receptors exhibit
- specificity
- competition
- saturation

Author

cbennett

197772

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Bio 220 - Chapter 6 - Communication, Integration, and Homeostasis

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Bio 220 - Chapter 6

Updated

2013-02-04T06:47:31Z

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